Being a Sunday I was lying in bed early this morning pondering life when I was reminded that we had 2 short power cuts in a row the night before due to me overdoing the electric heaters here in our cave in Spain where we’re having a short break. The laptop of course survived no problem due to internal battery but the Raspberry Pi went stone cold dead on me.
It occurred to me as I load more and more onto this tiny computer including a MYSQL database, that such cuts could do damage to the microSD card and indeed people have said that occasionally they go bad.
It occurred to me as I was sitting starting at one of the many unused “emergency power” solutions I have for my phone lying around that one of these would make an ideal “uninterruptable power supply” for the Pi. Indeed a very trivial script attached to one of the input pins could easily monitor the incoming power and do a nice, graceful shut down in the event of power loss.
I have one of those “Juicebar” devices, half the size of the Pi that accepts USB power and/or solar charge and with maybe 200ma capability could easily keep the Pi running for half an hour or more. Aside from the obvious advantage of protecting against power loss, I have no doubt these units will also protect to some extent from power surges.
And so that’s the plan. One wasted piece of kit lying around doing nothing could now save the bacon next time we have a power cut. These devices can be had for as little as £2.99 from Ebay (minus the solar panel) so really it just makes sense.
Up market at £10, the solar chargers come with 10,000maH capacity – that’s well over a day of operation and the solar panel can actually make a small contribution to the running costs!
Update March 26,2015: Just as has been mentioned it has come to my attention that many designs of these power systems will NOT allow you to use them in this way - you'll have to test. I have 4 such supplies - two will act as uninteruptables, the other two will not charge and be used at the same time (which seems a bit daft).
Update June 24,2015: http://www.banggood.com/30000mAh-Solar-Charger-Battery-Power-Bank-For-iPhone6-Smartphone-p-919239.html - this one’s a winner – no guarantees though.